Brake actuator and method of manufacture

ABSTRACT

A method and apparatus is disclosed for securely attaching existing conventional central adaptors for air brake actuators to service brake housings, emergency brake housings, or both, that are made from a metal that is dissimilar to that of the adaptor without major modification to either the housing or the adaptor. An annular shoulder with an elongated annular flange above it is provided on the steel part, and the aluminum part is provided with a small outwardly extending annular lip. A flexible diaphragm is first placed directly on the shoulder of the selected steel part. The aluminum part is then placed on top of the diaphragm such that the annular lip of the aluminum part fits inside the annular flange of the steel part. A slightly deformable annular steel piece is placed around the aluminum part so that it comes to rest against the annular aluminum lip while also touching the annular steel flange of the steel part. One or more breaks may be provided in the annular steel piece in order to allow it to be opened sufficiently to fit around the aluminum part. A weld is then applied to connect the annular steel piece(s) to the annular flange, thereby holding the aluminum or steel adaptor and diaphragm securely in place.

This application is a continuation-in-part of application Ser. No.08/662,993 filed on Jun. 13, 1996, now U.S. Pat. No. 5,758,564.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to spring brake actuators used oncommercial trucks, and more particularly to an apparatus and method forattaching either the outer spring brake housing, the outer service brakehousing, or both, of a spring brake actuator to a central adaptor madeof the same or a dissimilar metal.

2. Description of the Prior Art

Various forms of pneumatic vehicle spring brake actuators have beenintroduced over the years primarily for use in the trucking industry. Atypical actuator includes a service brake portion which is used forslowing or stopping a vehicle, and may also include an emergency orparking brake portion. The service brake portion is characterized by aclosed housing which contains a movable diaphragm stretched across theinside. One side of the diaphragm is connected to a centrally locatedslidable push rod which extends out of the housing for attachment to thebrakes of the vehicle. On the other side of the diaphragm a sealedchamber is formed within the housing.

An opening is provided in the sealed chamber for connection to apneumatic (air) pressure source usually provided by an on-board aircompressor. The brakes of the vehicle can be applied by introducingsufficient pneumatic pressure into the sealed chamber to act against theservice brake diaphragm which moves the push rod out. A small returnspring is provided inside the housing around the push rod to urge it toretract when the air pressure behind the diaphragm is reduced.

When employed, a typical emergency brake portion is attached directlybehind or made a part of the service brake assembly. The emergency brakeis a separate closed housing which contains a heavy compression springand a second movable diaphragm in sealed contact with a slidable centralrod which communicates directly with the push rod of the service brake.

A second sealed chamber is formed inside the emergency brake housing onone side of the diaphragm, and the heavy compression spring is deployedon the opposite side. As with the service brake, the sealed chamber ofthe emergency brake is connected to the on-board pneumatic source of thevehicle. As long as sufficient air pressure is provided, the diaphragmin the emergency brake will remain fully extended thereby compressingthe large spring. However, should pressure fall, or should there be aleak in the sealed chamber, the diaphragm will be unable to hold thelarge compression spring in place. When this occurs, either slowly orquickly, the large compression spring will cause the push rod to extendout thereby applying the brakes of the vehicle.

Under normal conditions, when the vehicle is parked, the air pressure tothe emergency brake portion is cut off causing the large compressionspring to apply the brakes.

Because the spring brake assembly is a critical safety system, it has tobe designed and manufactured for exceptional reliability. Moreover,because the compression spring inside the spring actuator must exert asufficient force to apply a maximum braking force to the vehicleindependent of any external air pressure assistance from the servicebrake system, the spring in its compressed state stores sufficientkinetic energy to be lethal if the spring brake housing is openedwithout first taking adequate precautions to secure the spring in itscompressed state or to release the stored energy in a controlled manner.

It is conventional to fabricate the spring brake housing containing thecompression spring and diaphragm in two opposing sections (an aluminumadaptor housing, and a steel cap or cup) separated by the periphery ofthe diaphragm, with the two opposing sections being clamped togetherwith sufficient force to maintain an air-tight seal between thediaphragm and the housing. Since unauthorized opening of the housing ispotentially dangerous to the inexperienced mechanic, and sinceunauthorized re-sealing using defective seals or improper procedurescould result in a poor diaphragm seal or other internal defect, it isalso conventional to discourage unauthorized access, disassembly, andreassembly of the housing by appending a warning label to the housingand using a clamping means which is temper-resistant or at leasttamper-evident, so that a new clamping means, not readily available tounauthorized personnel, is required before the housing can bereassembled.

Because of the danger presented by the compression of the large springof these brake systems, numerous inventions have been patented whichprovide different ways of improving safety. Many of these inventions aredirected towards securing the assembly of the two halves of the housingbetween which the diaphragm is deployed.

A typical service brake actuator housing is made of two cups which formthe two halves. When combined with an emergency brake actuator, thehousing has three distinct parts: a lower cup which forms the bottom ofthe service brake actuator, an upper cup which forms the top of theemergency brake actuator, and an hourglass-shaped central body oradaptor which is provided between them. The adaptor makes up the tophalf of the service brake housing, and the bottom half of the emergencybrake housing. Normal positioning of the two brake diaphragms results inthe adaptor being part of the sealed chambers of both the service brakeand the emergency brake. As a result, it is common for the adaptor toinclude the openings into each chamber for attachment to the pneumaticpressure source for the brakes.

The below-listed United States and foreign patents are known to exist:

    ______________________________________                                        No.     Patent No.                                                                              Date          Inventor                                      ______________________________________                                        1       2,541,205 February 13, 1951                                                                           Christophersen                                2       3,101,133 August 20, 1963                                                                             House                                         3       7308049.6 1973          Bosch (German)                                4       028074    June 27, 1978 Girling (G.B.)                                5       4,850,263 July 25, 1989 Rumsey                                        6       4,960,036 October 2, 1990                                                                             Gummer                                        7       5,062,455 November 5, 1991                                                                            Schurter                                      8       5,067,391 November 26, 1991                                                                           Choinski                                      9       5,193,432 March 16, 1993                                                                              Smith                                         10      5,205,205 April 27, 1993                                                                              Choinski                                      11      5,285,716 February 15, 1994                                                                           Thompson                                      12      5,315,918 May 31, 1994  Pierce                                        13      5,353,688 October 11, 1994                                                                            Pierce                                        ______________________________________                                    

These patents disclose different methods and apparatus for attachment ofthe two halves or cups of a brake housing. Annular clamps are taught inU.S. Pat. No. 2,541,205 to Christophersen; U.S. Pat. No. 4,960,036 toGummer, et al; and U.S. Pat. No. 5,193,432 to Smith. Such clamps arebulky and cumbersome in that the flanges, nuts and bolts used forconnection may not easily fit into the cramped brake area of a vehicle.

Various ways of crimping or bending the edge flanges of the two housingcups are taught in U.S. Pat. No. 3,101,133 to House; a German PatentApplication No. G 73 08 049.6 filed by Bosch; and U.S. Pat. No.4,850,263 to Rumsey. The Rumsey patent utilizes overlapping lips whereone is spinned over the other and bent into position by use of the latheor other suitable machine. Each of these devices is limited to the useof a strong bendable metal such as steel.

The three U.S. patents to Gummer and Choinski (U.S. Pat. Nos. 4,960,036;5,067,391; and 5,205,205) each disclose use of a clamp ring, use of ametal spun annular crimp of a flange on one of the housing cups, and theuse of a separate circular channel clamp for attachment of the housingcups. Clamp rings are bulky and dangerous as noted above; and, althoughthe circular channel clamp is a more permanent structure, it, as well asthe metal spun flanges, are again limited to use with steel.

The use of a snap ring for attachment is shown in U.S. Pat. No.5,353,688 to Pierce, et al, and in U.K. Patent No. GB 2,000,225A toGirling Midland, etc. U.S. Pat. No. 5,315,918 to Pierce disclosesseveral methods of attachment including bayonet, screw thread, slotsplus pins, and welds. Each of these methods of attachment requires thatthe cup and/or adaptor be uniquely modified in order to hold or acceptsuch things as the snap ring, the pins, the screw threads, the slots,etc. Such adaptations render the cup and adaptor parts unusable exceptwith correspondingly adapted parts, thereby severely limiting overalluse, especially for repair and reuse.

The welding together of two halves of like material is shown in U.S.Pat. No. 5,062,455 to Schurter and U.S. Pat. No. 5,285,716 to Thompson.

It is desirable to be able to use adaptor and/or housing cup parts inbrake actuators that are cast from aluminum as opposed to die pressedfrom steel sheets. However, attaching together such parts made fromdissimilar metals has heretofore only been accomplished by use ofannular clamps or the like. The ears, nuts and bolts of such clampscreate significant clearance problems in the close tolerances of thebrake area of a vehicle, making such methods of attachment unattractive.

Because of its hourglass shape, making an adaptor from steel requiresthe welding together of two halves. There is great expense involved increating the necessary tooling to make these two halves, and thenattaching them together. However, the price of aluminum can make it anattractive alternative to steel as a material to make the adaptor from.

It is also desirable for a brake manufacturer or remanufacturer to beable to use its conventional existing aluminum molds, or its existingsteel tooling, to create adaptor or housing cup pieces that may be moresecurely attached to existing adaptors or housing cups made of adissimilar metal. Thus, it is equally desirable to have a secureattachment device that does not require retooling of the parts that areto be attached together.

Casting the adaptor or housing cup pieces from aluminum is alsodesirable in that, compared to steel, many different molds may be easilyand cheaply created for the various sized pieces.

In order to avoid increasing labor and service costs, it is common for abrake actuator having a single worn out component (e.g. a diaphragm) tosimply be replaced in its entirety by another brake actuator, as opposedto repairing the actuator or replacing the worn out part in the field.When this occurs, the remaining parts of the old brake actuator,particularly the housing cups and adaptor, should be reusable forremanufacturing. It is therefore desirable to have a secure attachmentmethod and device for the adaptor and housing cups that gives the brakeactuator a long useful life, yet allows the adaptor and housing cups tobe disassembled without significant damage in order that they may bereused or remanufactured into brake actuators with correspondingly longuseful lives.

The problem presented is using aluminum adaptors or housing cups inspring brake assemblies and securely attaching them to their steelcounterparts. The present invention provides such a method andapparatus, while at the same time accomplishing many of the desirableconditions described above.

SUMMARY OF THE INVENTION

The present invention provides both a method and apparatus, as well asseveral alternatives, for securely attaching conventional centraladaptors for air brake actuators to service brake housings, emergencybrake housings, or both, made from a metal that is dissimilar to that ofthe adaptor without major modification to either the housing or theadaptor. The open end of the steel part (i.e. adaptor or housing cup)requires an annular shoulder with an elongated annular flange above it,which is a minor change. The open end of the aluminum part (i.e. thecorresponding housing cup or adaptor, respectively) requires a smalloutwardly extending annular lip, which many currently have. The outsidediameter of the annular lip must be smaller than the inside diameter ofthe annular flanges.

A flexible diaphragm is first placed directly on the shoulder of theselected steel part. The aluminum part is then placed on top of thediaphragm such that the annular lip of the aluminum part fits inside theannular flange of the steel part. It is not possible to securely weldsuch dissimilar metals together; however, it is possible to weld steelto steel. Accordingly, at least one slightly deformable annular steelpiece is also provided. The piece may have a single break therein, ormultiple breaks resulting in multiple pieces. The piece (or pieces) isplaced around the aluminum part so that it comes to rest against theannular aluminum lip while also touching the annular steel flange of thesteel part. The one or more breaks in the piece are necessary to allowit to be opened sufficiently to fit around the aluminum part. To theextent that the diameters of the two ends of the adaptor are different,the annular piece for use on the larger diameter end may be continuous(having no break therein) since it will fit over the smaller diameterend. A weld is then applied to connect the annular steel piece(s) to theannular flange, thereby holding the aluminum or steel adaptor anddiaphragm securely in place. The weld may be continuous or in partsaround the diameter.

Since it is important to obtain a secure seal around the diaphragm, theoutside edge of the diaphragm may be slightly thicker than its remainingcross section. Substantial force exceeding 1000 pounds is applied to theadaptor and housing as they are welded together using the annular steelpiece. This force compresses and deforms the outside edge of thediaphragm causing an airtight seal. The weld is applied to the steelshoulder flange as remote as possible from the diaphragm in order toavoid damaging or melting it. The shoulder of the steel part may beplaced in a heat sink during the welding process to help prevent damageto the diaphragm. However, the heat sink may not be necessary dependingupon the material used to make the diaphragm.

The preferred embodiment of the present invention generally will notrequire any bulky clamps, or any special modifications to the adaptor.It provides a strong and secure attachment between the adaptor andhousing, and an airtight seal for the diaphragm. The welded annularsteel piece may be later removed without damage to the aluminum or steelparts allowing these parts to be reused with another brake housing.

It is therefore a primary object of the present invention to provide amethod and apparatus for securely attaching a central aluminum or steeladaptor piece to either a steel service brake or steel emergency brakehousing of an air brake actuator.

It is also a primary object of the present invention to provide a methodand apparatus for securely attaching a central steel adaptor piece toeither an aluminum service brake or aluminum emergency brake housing ofan air brake actuator.

It is also a primary object of the present invention to provide a methodand apparatus for assuring a tight seal of the diaphragm between thealuminum or steel adaptor piece and either the service brake oremergency brake housing of an air brake actuator.

It is a further important object of the present invention to provide amethod and apparatus for securely attaching an aluminum or steel adaptorpiece to a selected steel brake housing by use of an annular steel piecethat is fitted over said adaptor and welded to said housing.

It is a further important object of the present invention to provide amethod and apparatus for securely attaching a steel adaptor piece to aselected aluminum brake housing by use of an annular steel piece that isfitted over said housing and welded to said adaptor.

It is a further important object of the present invention to provide amethod and apparatus for reusing an aluminum or steel adaptor piece thatis held in place by the welding onto the steel brake housing of anannular steel piece such that when said welded steel piece is removedsaid adaptor piece is preserved for reuse.

It is a further important object of the present invention to provide amethod and apparatus for reusing an aluminum or steel housing piece thatis held in place by the welding onto the steel adaptor of an annularsteel piece such that when said welded steel piece is removed saidhousing piece is preserved for reuse.

It is a further important object of the present invention to provide amethod and apparatus for securely attaching an aluminum or steel adaptorpiece to a selected steel brake housing by use of an annular steel piecethat is fitted over said adaptor and welded to said housing such thatwhen said welded steel piece is removed said adaptor piece and or saidhousing is preserved for reuse.

It is a further important object of the present invention to provide amethod and apparatus for securely attaching an aluminum or steel housingpiece to a selected steel adaptor by use of an annular steel piece thatis fitted over said housing and welded to said adaptor such that whensaid welded steel piece is removed said housing piece and/or saidadaptor is preserved for reuse.

It is a further important object of the present invention to provide amethod and apparatus for securely attaching an aluminum or steel adaptorpiece to a selected steel brake housing without cumbersome and spaceconsuming annular clamps having ears, nuts or bolts.

It is a further important object of the present invention to provide amethod and apparatus for securely attaching an aluminum or steel adaptorpiece to a selected steel brake housing that does not require any majormodification of the tooling necessary to create the adaptor or housing.

It is a further object of the present invention to provide a variety ofdifferent annular steel pieces each having at least one break thereinfor use in securely attaching an aluminum or steel adaptor piece to aselected brake housing of an air brake actuator.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central aluminum or steel adaptorpiece to either a steel service brake or steel emergency brake housingof an air brake actuator utilizing an annular formed steel piece held inplace using rivets, screws or pins.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central steel adaptor piece to eitheran aluminum service brake or aluminum emergency brake housing of an airbrake actuator utilizing an annular formed steel piece held in placeusing rivets, screws or pins.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central aluminum or steel adaptorpiece to either a steel service brake or steel emergency brake housingof an air brake actuator utilizing an annular clamp made of formed steeland a weld.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central steel adaptor piece to eitheran aluminum service brake or aluminum emergency brake housing of an airbrake actuator utilizing an annular clamp made of formed steel and aweld.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central aluminum or steel adaptorpiece to either a steel service brake or steel emergency brake housingof an air brake actuator utilizing an annular steel piece and a set ofnotched tangs which correspond to openings in the housing cap.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central steel adaptor piece to eitheran aluminum service brake or aluminum emergency brake housing of an airbrake actuator utilizing an annular steel piece and a set of notchedtangs which correspond to openings in the housing cap.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central aluminum or steel adaptorpiece to either a steel service brake or steel emergency brake housingof an air brake actuator utilizing a layer of lamanate carbon fiber.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central steel adaptor piece to eitheran aluminum service brake or aluminum emergency brake housing of an airbrake actuator utilizing a layer of lamanate carbon fiber.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central aluminum or steel adaptorpiece to either a steel service brake or steel emergency brake housingof an air brake actuator utilizing an L-shaped annular steel piececo-molded with the cast aluminum adaptor piece and welded to thehousing.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central steel adaptor piece to eitheran aluminum service brake or aluminum emergency brake housing of an airbrake actuator utilizing an L-shaped annular steel piece co-molded withthe cast aluminum housing piece and welded to the adaptor.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central aluminum or steel adaptorpiece to either a steel service brake or steel emergency brake housingof an air brake actuator utilizing a set of discontinuous clips made offormed steel and welds.

It is a further object of the present invention to provide a method andapparatus for securely attaching a central steel adaptor piece to eitheran aluminum service brake or aluminum emergency brake housing of an airbrake actuator utilizing a set of discontinuous clips made of formedsteel and welds.

Additional objects of the invention will be apparent from the detaileddescriptions and the claims herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut away side view of the lower portion of acombination service brake and emergency brake actuator showing detail ofthe attachment of the steel adaptor to the aluminum housing cap of theemergency brake.

FIG. 2 is an exploded perspective view showing the assembly of acombination service brake and emergency brake actuator of the presentinvention.

FIG. 2A is a side view showing an assembled combination service brakeand emergency brake actuator.

FIG. 3 is an enlarged cut away partial side view of a connection betweenthe steel adaptor and the aluminum housing cap of the emergency brakeutilizing an annular ring and weld.

FIG. 4 is an enlarged cut away partial side view of an alternativeconnection between the steel adaptor and the aluminum housing cap of theemergency brake utilizing an annular steel piece and weld.

FIG. 5 is an enlarged cut away partial side view of an alternativeconnection between the aluminum cast adaptor and the steel housing capof the emergency brake utilizing an annular formed steel piece held inplace using rivets, screws or pins.

FIG. 6 is an enlarged cut away partial side view of an alternativeconnection between the aluminum cast adaptor and the steel housing capof the emergency brake utilizing an annular clamp made of formed steeland weld.

FIG. 7 is an enlarged cut away partial side view of an alternativeconnection between the steel adaptor and the aluminum housing cap of theemergency brake utilizing an annular steel ring and weld.

FIG. 8 is an enlarged cut away partial side view of an alternativeconnection between the steel adaptor and the aluminum housing cap of theemergency brake utilizing an annular steel piece and weld.

FIG. 9 is an enlarged cut away partial side view of an alternativeconnection between the steel adaptor and the aluminum housing cap of theemergency brake utilizing an annular steel piece and weld.

FIG. 10 is an enlarged cut away partial side view of an alternativeconnection between the aluminum cast adaptor and the steel housing capof the emergency brake utilizing an annular formed steel piece held inplace using rivets, screws or pins.

FIG. 11 is an enlarged cut away partial side view of an alternativeconnection between the aluminum cast adaptor and the steel housing capof the emergency brake utilizing an annular steel piece and a set ofnotched tangs which correspond to openings in the housing cap.

FIG. 12 is an enlarged cut away partial side view of an alternativeconnection between the aluminum cast adaptor and the steel housing capof the emergency brake utilizing a set of die punched tangs in thehousing cap.

FIG. 13 is an enlarged cut away partial side view of an alternativeconnection between the steel adaptor and the aluminum housing cap of theemergency brake utilizing an annular steel piece and weld.

FIG. 14 is an enlarged cut away partial side view of an alternativeconnection between the aluminum cast adaptor and the steel housing capof the emergency brake utilizing a layer of lamanate carbon fiber.

FIG. 15 is an enlarged cut away partial side view of an alternativeconnection between the aluminum cast adaptor and the steel housing capof the emergency brake utilizing an annular clamp made of formed steelusing an indented adaptor base.

FIG. 16 is an enlarged cut away partial side view of an alternativeconnection between the steel adaptor and the aluminum housing cap of theemergency brake utilizing an L-shaped annular steel piece co-molded withthe die-casted aluminum and welded to the housing.

FIG. 17 is an enlarged cut away partial side view of an alternativeconnection between the steel adaptor and the aluminum housing cap of theemergency brake utilizing an annular steel piece and weld.

FIG. 18 is an enlarged cut away partial side view of an alternativeconnection between the steel adaptor and the aluminum housing cap of theemergency brake utilizing an L-shaped annular steel piece welded to thehousing.

FIG. 19 is an enlarged cut away partial side view of an alternativeconnection between the aluminum cast adaptor and the steel housing capof the emergency brake utilizing a set of discontinuous clips made offormed steel and welds.

FIG. 19A is an enlarged fragmentary side view of a discontinuous clipwelded to the steel housing.

FIG. 20 is a side view of a service brake assembly.

FIG. 21 is a top perspective view of an annular steel member showing asingle opening therein.

FIG. 21A is a top perspective view of an annular steel member showingmultiple openings therein.

FIG. 21B is a top perspective view of an annular steel member showing noopenings therein.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the drawings wherein like reference characters designatelike or corresponding parts throughout the several views, and referringparticularly to FIGS. 1, 2, 2A and 7 it is seen that the inventionincludes an air brake actuator, generally 30, including a service brakehousing 31, an emergency brake housing 32, and a central cylindricaladaptor base 35 between the service brake and emergency brake housings.A slidable push rod 25 extends outward from the service brake housingfor connection to the brakes of the vehicle. Openings 24 are provided inthe adaptor for connection to the pneumatic pressure source.

Referring to FIG. 1 and the detail of FIG. 7, it is seen that emergencyspring brake adaptor 35 includes an annular shoulder 33 and an annularaxially-extending flange 34, and that housing 32 includes an outwardlyextending lip 36. A flexible diaphragm 40 is also provided which mayhave a thickened outer circumferential edge 41. An annular steelretaining piece 45 which may have one or more openings 46 therein (seeFIGS. 21, 21A and 21B) is provided between the upper flange 34 ofadaptor 35 and housing 32, just above lip 36. Piece 45 is welded to thetop of flange 34 at 49. This same configuration may also be used toattach the service brake housing 31 to the opposite end of the adaptor35.

An exploded view of a combination service brake and emergency brakeactuator, including the sub-assembly parts, is shown in FIG. 2. Theseinclude the main compression spring 27, an intermediate push rod 28,return springs 29, and push rod 25 with plate, and disc 23.

FIGS. 3, 4, 7, 8, 9, 13 and 17 show different embodiments of the brokenannular piece 45. In FIG. 3, as in FIG. 7, piece 45 is an annular ringhaving a round cross section. A second annular lip 37 is provided onaluminum housing 32 in the embodiment of FIG. 3 for securely holdingpiece 45 in place. FIG. 4 shows a molded annular steel piece 45 having across section in the shape of a modified "Z" where one end slides snuglyover flange 34, and the other end conforms with lip 36 on housing 32. Aresistance spot weld is made where piece 45 fits over the top of axiallyextending flange 34. FIG. 8 shows piece 45 having a semi-circular crosssection so that a flat area is adjacent to flange 34, and weld 49 ismade at the top of flange 34. FIG. 9 shows a molded annular piece 45having a cross section in the shape of a modified "V" with a flatoutside adjacent to flange 34, and a rounded inside conforming with theshape of lip 36 on housing 32. FIG. 13 shows annular piece 45 having arectangular cross section with one flat side adjacent to flange 34. FIG.17 shows piece 45 as a taller rectangle with more surface area touchingflange 34 while the bottom of rectangle 45 holds lip 36 in place.

FIGS. 5 and 10 show a molded annular steel piece 45 which is attached toflange 34 using a rivet, pin or screw 51. In FIG. 10, piece 45 has across section in the shape of a modified "Z" where one end slides snuglyover flange 34, and the other end conforms with lip 36 on housing 32.

In FIGS. 6, 15 and 19 piece 45 is in the form of an annular C-shapedclamp made of formed steel. It is to be noted that in these threeembodiments, housing 32 has no annular flange 34, and diaphragm 40 issandwiched between housing 32 and adaptor 35 and held in place by clamppiece 45. However, instead of being spin molded or deformed forattachment, as shown in FIG. 6, piece 45 is welded along the bottom edgeat 49. A set of discontinuous C-shaped clips 47 may be used instead of asingle piece 45 as shown in FIG. 19 and 19A. Alternatively, the bottomof piece 45 may be exaggerated, as shown in FIG. 15, so that no weld isrequired for attachment.

FIGS. 11 & 12 show two related embodiments utilizing a set of tangsinstead of a weld. FIG. 11 shows the modified "Z" shaped piece 45 ofFIGS. 4 and 10 in which a set of protruding tangs 52 are provided whichfit into a set of corresponding notches 38 in flange 34. In FIG. 12, aset of protruding tangs 53 are die punched into flange 34 whereby lip 36of adaptor 35 is snapped into place.

In FIG. 14, lamanate carbon fiber 55 is molded into an annular ringaround flange 34 and the lower leg and lip 36 of adapter 35.

In FIGS. 16 and 18, the cross section of piece 45 has an L-shape, andlips 36 and 37 of adapter 35 define a pronounced opening into which thehorizontal lower end of L-shaped piece 45 fits. The vertical end ofpiece 45 is adjacent to flange 34 allowing for weld 49 at the top. Inthe embodiment of FIG. 16, the L-shaped piece is co-molded with thealuminum adaptor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the preferred embodiment, the housing cups of the present inventionare made of aluminum and cast in an appropriate mold. However, thepresent invention works equally well with any metal housing. Tooling foran aluminum housing is far less expensive than forming the same partfrom a steel sheet. Openings for attachment of each chamber to thepneumatic source are provided in the adaptor. An outside annular lip isprovided at each end of the housing. The adaptor between the servicebrake and emergency brake is made of steel. The open ends of the adaptoreach include an annular shoulder adjacent to an axially extendingannular flange. The inside diameters of the annular flanges should beslightly larger than the outside diameters of the annular lips on thecorresponding ends of the housings so that said lips fit snugly intosaid flanges. Each annular steel piece 45 should have a diameter that isapproximately the same as the corresponding annular lip on either theemergency brake or service brake housing. Each piece 45 may require atleast one opening therein to allow it to be easily placed around themain body of each housing, since the lips at the ends of each housingmay prevent a solid piece from such engagement. However, there may bemore than one break such that piece(s) 45 may be more easily placedaround the given annular lip of the housing. At least one solid piece 45may be used if the diameters of the two ends of the cylindrical adaptorare of sufficiently different sizes.

In the preferred embodiment shown in FIG. 7, an annular lip 35 isprovided upon which discontinuous annular piece 45 comes to rest. Anannular weld (that is discontinuous only at the break(s) 46 in piece 45)between piece 45 and flange 34 is preferred for maximum attachmentsecurity. In the preferred embodiment of FIG. 3, a second annular lip 37is provided on adaptor 35 in order to form a more secure connectionbetween retaining piece 45 and adaptor 35.

In the alternative embodiments of FIGS. 4, 7, 8, 9, 13 and 17 annularsteel piece 45 has different cross sectional shapes, ranging frommodified "Z" and other poly-sided shapes (including a modified "V"),which conform closely with the shapes of flange 34 and lip 36, to round,semi-circular and rectangular cross sections each having operableadvantages such as low cost of manufacture, ease of assembly, and easein formation. The annular steel piece 45 of each of these embodiments iswelded to flange 34.

In the alternative embodiments of FIGS. 5 & 10 a molded annular steelpiece 45 is attached to flange 34 using a rivet, pin or screw 51.

In the alternative embodiments of FIGS. 6, 15 and 19 (and 19A) piece 45is in the form of an annular C-shaped clamp made of formed steel. Thebottom of piece 45 is welded to flange 34 as shown in FIG. 6; and aseries of discontinuous clips 47, each welded at the bottom, are shownin FIGS. 19 and 19A. Alternatively, the bottom of piece 45 may beexaggerated, as shown in FIG. 15, so that no weld is required forattachment. In each of these three embodiments, housing 32 has noannular flange 34, and diaphragm 40 is sandwiched between housing 32 andadaptor 35 and held in place by clamp piece 45.

In the alternative embodiments of FIGS. 11 and 12 a set of tangs areused instead of a weld. The embodiment of FIG. 11 uses a set ofprotruding tangs 52 which fit into a set of corresponding notches 38 inflange 34. In the embodiment of FIG. 12, a set of protruding tangs 53are die punched into flange 34 whereby lip 36 of adaptor 35 is snappedinto place.

In the alternative of FIG. 14, lamanate carbon fiber 55 is molded intoan annular ring around flange 34 and the lower leg and lip 36 of adapter35.

The preferred method of attaching the aluminum housing to the adaptorrequires that the adaptor have an annular shoulder 33 and an axiallyprotruding flange 34. The adaptor may be created by stamping from asteel sheet, or another suitable process. The housing is cast fromaluminum, although in alternative embodiments it may be made from steelor other ferrous or non-ferrous material. The housing should have anoutwardly extending annular lip 36 the outside diameter of which isslightly smaller than the inside diameter of flange 34. The flanged lipcan have a configuration that is angled, grooved, drilled, chamfered,machined or as cast. Finally, an annular retaining piece 45 is providedwhich may be formed, cast, stamped, rolled, punched or machined. It maybe made from ferrous or non-ferrous material, and may have at least onebreak therein to facilitate placing it over the adaptor base. Thecross-sectional shape of piece 45 may be round, square, rectangular,semi-circular, strip, or poly-sided. It should have a diameter roughlythe same as the annular lip 36 such that it fits snugly inside flange 34with good metal-to-metal contact. It should also have good metal tometal contact where it overlaps lip 36.

The following common components of the brake actuator system are alsoassembled into the housing: the main compression spring; a flexiblediaphragm 40 having roughly the same diameter as the lip 36; an adaptorbase return spring; an intermediate push rod; a push rod plate; O-rings;a pressure plate; a screw and push rod; and grease. It is preferred thatthe diaphragm may have a slightly thickened outer edge.

The first step in attaching the adaptor to the emergency brake housing32 is placement of the adaptor in a cold environment such as a heat sinkwith its open flanged end facing upward. The main spring 27 iscompressed into the housing and secured by a retaining tool in afixture. The adaptor base sub-assembly is made of the return spring 29,intermediate push rod 28, push rod plates, O-rings, screws, push rod 25,and grease (See exploded view of FIG. 2). Diaphragm 40 is then insertedinto the adaptor such that its thickened edges are along the shoulderbelow the annular flange. The sub-assembly is then placed into theadaptor such that the annular lip 36 fits snugly inside annular flange34, and is resting on top of the thick edges of diaphragm 40. Force inexcess of 1000 pounds is then applied to these components using either apneumatic, mechanical, hydraulic or electrical ram sufficient to createa seal between the sub-assembly and the diaphragm 40. Then, annularretaining piece(s) 45 are placed around housing 32 so that it (they)come into contact with the annular lip 36 of the housing 32 insideflange 34. A second force is then applied to the retainer piece itselfwhich causes good metal-to-metal contact between the piece(s) 45 boththe flange 34 and lip 36. This and can be accomplished using mechanicalclamps, electromagnetism, or external pressure. While under this secondforce, piece 45 is fused to the flange of the adaptor. This may beaccomplished using a gas tungsten arc welder, or other processes such asgas metal arc welding, arc welding and shield arc welding, oxyfuel gaswelding, brazing, soldering, spot, laser beam or the like. Asemi-automated welding apparatus may be used which incorporates athermally cooled block (heat sink) that is shaped to reduce the thermalconduction into the diaphragm. This heat sink helps prevent deformationor destruction of the diaphragm from the heat of the welding process.The weld times, speeds, wire feeds, gas flows, power sources andvoltages are parameters set to reduce the thermal load into thediaphragm. The power sources can be either continuous or pulse phasewelders. The wire used in the welding process could be either solid orflux cored. After a brief cooling period, the pressure is released, andthe attached adaptor and housing assembly may be removed, tested,cleaned and painted.

A similar series of steps are followed to assemble the service brakehousing 31 and attach it to the opposite end of the adaptor 35 (seeexploded view of FIG. 2).

The fusing of part 45 may be accomplished in at least two differentways. In the preferred method, part 45 is tack fused to the flange whilethe second force is still holding part 45 in place. This force is thenremoved, making all of part 45 available for fusing. In the othermethod, full fusing is performed while the second force is beingapplied.

Several alternative embodiments of the apparatus are also available.Retaining piece 45 may be made in one of several differentconfigurations having different cross sectional shapes such as circular,semi-circular, rectangular, square or poly-sided. A second annular lip37 may be provided on housing 32 as shown in FIG. 3 in order to form amore secure connection between retaining piece 45 and housing 32,especially during the fusing process. Retainer piece 45 may be in theform on an "L" which is co-molded with the cast aluminum housing pieceas shown in FIG. 16. This embodiment also includes the second annularlip 37 which holds co-molded piece 45 in place.

Another embodiment of both the method and apparatus utilizes pins,screws or rivets to connect the retainer piece 45 to the flange 34, asshown in FIGS. 5 and 10, without the use of any welding. Yet anotherembodiment of both the method and apparatus employs the use of a set oftangs 53 which are die punched into flange 34 so that lip 36 of adaptor35 may be snapped into place (see FIG. 12). Still another alternativeembodiment employs a set of protruding tangs 52 which fit into a set ofcorresponding notches 38 in flange 34 (see FIG. 10). Another embodimentutilizes a C-clamp that is either clipped or welded into place to holdthe housing to the adaptor (see FIGS. 6 and 15); this clamp may also bein the form of discontinuous clips which are each welded to the housing(see FIGS. 19 and 19A). Lamanate carbon fiber 55 may be molded into anannular ring around flange 34 and the lower leg and lip 36 of adapter 35as shown in FIG. 14.

The present invention is equally useful for either aluminum or steeladaptor parts 35. The present invention may also be used on suchproducts as piston brakes which use a solid piston rather than aflexible diaphragm.

It is to be understood that variations and modifications of the presentinvention may be made without departing from the scope thereof. It isalso to be understood that the present invention is not to be limited bythe specific embodiments disclosed herein, but only in accordance withthe appended claims when read in light of the foregoing specification.

We claim:
 1. A brake actuator comprising:a. an cylindrical adaptorhaving an annular shoulder and an axially protruding annular flange; b.a flexible diaphragm stretched across said adaptor on said shoulder; c.a brake housing cup having an annular lip at its edge provided over saiddiaphragm at said shoulder adjacent to said annular flange; d. anannular retaining piece provided over said lip and on the inside of saidflange; and e. at least one weld connecting said retaining piece to saidannular flange, for holding the lip of said housing securely againstsaid adaptor.
 2. The actuator described in claim 1 wherein a secondannular lip is provided on said housing in close proximity to the firstannular lip such that said annular retaining piece fits between saidlips.
 3. The actuator described in claim 1 wherein said retaining pieceis discontinuous.
 4. The actuator described in claim 1 wherein saidretaining piece has a circular cross section.
 5. The actuator describedin claim 1 wherein said retaining piece has a semi-circular crosssection.
 6. The actuator described in claim 1 wherein said retainingpiece has a rectangular cross section.
 7. The actuator described inclaim 1 wherein said retaining piece has a square cross section.
 8. Theactuator described in claim 1 wherein said retaining piece has anL-shaped cross section.
 9. The actuator described in claim 1 whereinsaid retaining piece has a cross section in the shape of a modified "V".10. The actuator described in claim 1 wherein said retaining piece has across section in the shape of a modified "Z".
 11. The actuator describedin claim 1 wherein said retaining piece has a poly-sided cross section.12. An apparatus for connecting a brake actuator adaptor and housingtogether comprising:a. a cylindrical adaptor having an annular shoulderadjacent to an axially protruding annular flange; b. a rounded flexiblediaphragm peripherally supported by said shoulder, said diaphragm havingapproximately the same diameter as the inside of said annular flange; c.a brake housing cup having an outwardly extending annular lip theoutside diameter of which is slightly smaller than the inside diameterof said annular flange peripherally supported by said diaphragm andshoulder; d. an annular steel retaining piece on said lip and insidesaid flange, said piece having a diameter approximately the same as saidannular lip; and e. at least one weld connecting said annular piece tosaid annular flange, for holding said adaptor securely against saidhousing.
 13. A method for assembling a spring brake actuator comprisingthe steps of:a. forming a cylindrical adaptor with an annular shoulderand an axially protruding annular flange; b. forming a spring brakeactuator housing cup with an outwardly extending annular lip at leastone end; c. forming an annular retaining piece having a diameterapproximately the same as said annular lip; d. placing the adaptor in acooled environment; e. inserting a flexible diaphragm into the adaptorsuch that its edges fit along said shoulder adjacent to said annularflange; f. inserting the housing cup into the adaptor such that theannular lip fits inside and against the annular flange, resting on topof the edges of the diaphragm; g. applying force to the adaptor andhousing sufficient to create a seal between the housing cup and thediaphragm; h. placing the annular retaining piece around the housing cuplip such that it comes into contact with both the lip and the inside ofthe flange; i. applying a second force to said retaining piece; and j.fusing the retaining piece to the flange of the adaptor.
 14. The methoddescribed in claim 13 wherein said annular retaining piece isdiscontinuous.
 15. A method for connecting a spring brake actuatorhousing to an adaptor comprising the steps of:a. forming a cylindricaladaptor with an annular shoulder and an axially protruding annularflange; b. forming a spring brake actuator housing cup with an outwardlyextending annular lip at one end, the outside diameter of which isslightly smaller than the inside diameter of said flange; c. forming anannular retaining piece having a diameter approximately the same as saidannular lip such that it fits snugly inside said flange with goodmetal-to-metal contact with both said flange and said lip; d. placingthe adaptor in a heat sink environment; e. compressing a main springinto the housing cup; f. creating a sub-assembly comprised of at leastthe following components: an adaptor base return spring, an intermediatepush rod, a push rod plate, a pressure plate, and a push rod; g.inserting a flexible diaphragm into the adaptor such that its edges fitalong said shoulder adjacent to said annular flange; h. inserting thehousing cup and sub-assembly into the adaptor such that the annular lipfits snugly inside the annular flange, resting on top of the edges ofthe diaphragm; i. applying force to the adaptor and housing sufficientto create a seal between the sub-assembly and the diaphragm; j. placingthe annular retaining piece around the housing cup lip such that itcomes into contact with both the lip and the inside of the flange; k.applying a second force to said retaining piece; and l. fusing theretaining piece to the flange of the adaptor.